Move Extension into extensions namespace

chrome/common/extensions/api/extension_api.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_EXTENSIONS_API_EXTENSION_API_H_
 #define CHROME_COMMON_EXTENSIONS_API_EXTENSION_API_H_
 #pragma once
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/string_piece.h"
 #include "base/values.h"
 #include "chrome/common/extensions/feature.h"
 #include "chrome/common/extensions/feature_provider.h"
 #include "chrome/common/extensions/url_pattern_set.h"
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 class Value;
 }
 
 class GURL;
-class Extension;
 class ExtensionPermissionSet;
 
 namespace extensions {
 
+class Extension;
 class Feature;
 
 // C++ Wrapper for the JSON API definitions in chrome/common/extensions/api/.
 //
 // WARNING: This class is accessed on multiple threads in the browser process
 // (see ExtensionFunctionDispatcher). No state should be modified after
 // construction.
 class ExtensionAPI : public FeatureProvider {
  public:
   // Returns a single shared instance of this class. This is the typical use
@@ skipping 137 matching lines @@
   // FeatureProviders used for resolving dependencies.
   typedef std::map<std::string, FeatureProvider*> FeatureProviderMap;
   FeatureProviderMap dependency_providers_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionAPI);
 };
 
 }  // extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_API_EXTENSION_API_H_